The present invention is related to cyclic phosphazenes.
Various phosphazenes are known in the art. For example, U.S. Pat. Nos. 3,316,330 and 3,234,304 disclose cyclic compounds corresponding to the formula: EQU P.sub.m N.sub.m R.sub.x R'.sub.y R".sub.z (I)
wherein R is m-trifluoromethoxyphenoxy, R' is phenoxy and R" is m-trifluoromethylphenoxy, m is an integer of from 3 to 7, x is at least one and the sum of x, y and z is 2m. The materials are disclosed to be useful as high temperature lubricants, working fluids and plasticizers. Additional examples of other substituted phosphazenes are disclosed in U.S. Pat. No. 3,136,727; European Patent Application 0241877; U.S. Pat. No. 3,280,222 and U.S. Pat. No. 3,459,838. These phosphazenes are also generally taught to be useful as lubricants and working fluids.
The demands placed on these materials and other existing lubricants are currently undergoing significant changes. Engines are being developed for automotive and aeronautic applications that have requirements dramatically different from those of engines currently in use. It is anticipated that these engines will operate at temperatures exceeding 250.degree. C. and will be constructed using materials new or different from those currently in use. Thus, what is needed are novel compounds useful as lubricants or lubricant additives that are stable at the high use temperatures while possessing the other properties required of lubricants.